Combined heat pump and air-conditioning apparatus and method

ABSTRACT

There is provided a combined heat pump and air-conditioning apparatus and method. There is a source of heat, a compressor having an input and an output, a heat exchanger , a condenser, an evaporator, and coolant conduits for connecting the source of heat to the evaporator. There are heat transfer medium conduits interconnecting the heat exchanger, the condenser and the evaporator. A valve is operatively connected to the medium conduits and connects the output of the compressor to the condenser and connects the heat exchanger to the input of the compressor during an air-conditioning mode where the heat exchanger operates as an evaporator. The valve operatively connects the output of the compressor to the heat exchanger and connects the input of the compressor to the evaporator during a heat pump mode where the heat exchanger acts as a condenser. In one example the heat exchanger is positioned to communicate with the interior of the vehicle and the apparatus and method alternatively cool or heat the interior of the vehicle depending upon the mode of operation thereof.

BACKGROUND OF THE INVENTION

This invention relates to heating and air-conditioning systems and, in particular, to combination heat pumps and air-conditioning systems.

Air-conditioning systems are conventionally installed in most vehicles, particularly in warmer climates. Usually the systems are only operational when the vehicle engine runs. However air-conditioning requirements may still exist when the engine is off. For example, it wastes a lot of fuel to maintain engine operation while the diesel vehicle is parked for a long period of time. However the operator of a tractor/trailer unit may require air-conditioning for the cab while he or she is resting. For this reason many diesel powered highway vehicles are equipped with auxiliary power units. These include a diesel engine which is relatively small compared with the main engine of the vehicle. Each auxiliary power unit (APU) conventionally includes a generator or alternator connected to the engine thereof. This provides electrical power to the vehicle while the main vehicle engine is off. The electrical power from the APU can be used to power an air-conditioner to maintain cooling of the cab while the vehicle is parked.

However, the vehicle may also require heating for the cab while the vehicle is parked. Theoretically this could be done by circulating liquid coolant from the APU engine through a heat exchanger in the cab. However this requires additional plumbing in the cab and it may be difficult to find space available for another heat exchanger. Also the engine of the APU may only provide sufficient heat if the engine is operating under a load. If no such load otherwise occurs, then it may be necessary to apply a load to the engine merely for purposes of generating sufficient heat. Obviously this wastes fuel.

An engine outputs energy in three different ways. Roughly one third of the energy goes to the mechanical, rotational output of the engine, which can be used for such purposes as running the APU generator. Another one third of the energy goes to exhaust. A final third is transferred to the engine coolant. Only this last third would normally be available for heating the cab of the vehicle.

Heat pumps have been used in the past to heat buildings and require a source of heat, for example heat obtained from the ground. Heat pumps are capable of transferring heat from a lower temperature body, such as the ground, to a higher temperature body, such as the interior of a building. This is done by applying energy, using a compressor, to compress a heat transfer medium such as a glycol/water mixture. Subsequently the heat transfer medium passes through a condenser where the medium is condensed by exchanging heat with the ambient air circulated through the condenser by a fan. Thus, the air in the building is heated. The liquefied heat transfer medium then passes through an expansion valve and flows through an evaporator where thermal energy is applied, by heat from the ground in the case of a conventional building-installed heat pump. The heated medium is then drawn into the compressor where it is compressed and the cycle continues.

Heat pumps have not been used traditionally in vehicles, in part because there is no obvious source of heat. Clearly vehicles move and accordingly connections to the ground are not possible.

SUMMARY OF THE INVENTION

According to one aspect of the invention, there is provided a combined heat pump and air-conditioning apparatus. There is a source of heat, a compressor having an input and an output, a heat exchanger, a condenser, an evaporator and first conduits for connecting the source of heat to the evaporator. There are heat transfer medium conduits interconnecting the heat exchanger, the condenser and the evaporator. A valve is operatively connected to the medium conduits and connects the output of the compressor to the condenser and connects the heat exchanger to the input of the compressor during an air-conditioning mode where the heat exchanger operates as an evaporator. The valve operatively connects the output of the compressor to the heat exchanger and connects the input of the compressor to the evaporator during a heat pump mode where the heat exchanger acts as a condenser.

According to another aspect of the invention, a combined heat pump and air-conditioning apparatus comprises a heat exchanger, a condenser, an evaporator, an internal combustion engine, and a compressor operatively connected to the engine. The compressor has an input port and an output port. There is also a valve, a first conduit connected to the output port of the compressor, a second conduit connected to the heat exchanger, a third conduit connected to the heat exchanger, a fourth conduit connecting the third conduit to the evaporator, a fifth conduit connected to the evaporator, a sixth conduit connected to the condenser, a seventh conduit connected to the input port of the compressor, an eighth conduit connected to the sixth conduit and the fifth conduit and a ninth conduit connected to the condenser and to the third conduit. Coolant conduits connect the engine to the evaporator for supplying heated engine coolant to the evaporator. There is a valve having a first port, a second port, a third port, a fourth port and a movable valve member for interconnecting the ports, the first port being connected to the seventh conduit, the second port being connected to the second conduit, the third port being connected to the first conduit and the fourth port being connected to the eighth conduit. The apparatus has an air-conditioning mode where the valve member connects the second port to the first port and connects the third port to the fourth port, whereby a heat transfer medium compressed by the compressor flows to the condenser through the first conduit, the eighth conduit and the sixth conduit. The heat transfer medium flows from the condenser to the heat exchanger through the ninth conduit and the third conduit and flows from the heat exchanger to the input port of the compressor through the second conduit and the seventh conduit. The apparatus has a heat pump mode where the valve member connects the third port to the second port and the fourth port to the first port, whereby the heat transfer medium compressed by the compressor flows to the heat exchanger through the first conduit and the second conduit, and flows from the heat exchanger to the evaporator through the third conduit and the fourth conduit. The heat transfer medium flows from the evaporator to the input port of the compressor through the fifth conduit, the eighth conduit and the seventh conduit.

According to a further aspect of the invention, there is provided a vehicle having an interior, an internal combustion engine and a combined heat pump and air-conditioning apparatus. The apparatus has a compressor with an input and an output, a heat exchanger communicating with the interior of the vehicle, a condenser, an evaporator and heat transfer medium conduits for a heat transfer medium. The medium conduits interconnect the heat exchanger, the condenser and the evaporator. Coolant conduits interconnect the evaporator and the engine for carrying coolant heated by the engine. A valve is operatively connected to the medium conduits and connects the output of the compressor to the condenser and connects the heat exchanger to the input of the compressor during an air-conditioning mode where the heat exchanger operates as an evaporator. The valve operatively connects the output of the compressor to the heat exchanger and connects the input of the compressor to the evaporator during a heat pump mode where the heat exchanger acts as a condenser.

According to a still further aspect of the invention, there is provided a method of heating and cooling a space having a heat exchanger and a fan for directing air over the heat exchanger into the space. The method comprises cooling the space during an air-conditioning mode by connecting an output of a heat transfer medium compressor to a condenser, connecting the condenser to the heat exchanger and connecting the heat exchanger to an input of the compressor, whereby the heat exchanger and fan act as an evaporator for cooling the space. The space is heated during a heat pump mode by connecting the output of the compressor to the heat exchanger, connecting the heat exchanger to an evaporator and connecting the evaporator to the input of the compressor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a combined air-conditioner and heat pump apparatus for a vehicle, according to an embodiment of the invention, showing the apparatus in an air-conditioning mode;

FIG. 2 is a diagram similar to FIG. 1 showing the apparatus in a heat pump mode; and

FIG. 3 is a partly diagrammatic, isometric view of the apparatus of FIGS. 1 and 2.

DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS

Referring to the drawings, these show a combined heat pump and air-conditioning apparatus 10 according to an embodiment of the invention. The apparatus includes a heat exchanger 12 which, as detailed below, acts alternatively as an evaporator or condenser depending upon the mode of operation of the apparatus. Air driven past the heat exchanger 12 by a fan 16, adjacent to the heat exchanger, is discharged into interior 20 of cab 22 of a vehicle. The heat exchanger in this particular example may be a conventional or pre-existing heat exchanger and fan which normally function as an evaporator for an air-conditioning system powered by an auxiliary power unit for the vehicle. In one particular embodiment the heat exchanger may comprise a second coil in a pre-existing evaporator installed in the vehicle for the conventional air-conditioning system powered by the vehicle engine, as disclosed in the co-pending patent application entitled AUXILIARY AIR-CONDITIONING APPARATUSES AND METHODS FOR VEHICLES and assigned to Teleflex Canada Incorporated.

The apparatus also includes an air-conditioning condenser 24 with a fan 25, a heat pump evaporator 26 and a compressor 28 driven by engine 30 which, in this example, is an auxiliary engine for the vehicle forming part of an auxiliary power unit for the vehicle. The evaporator heats a heat transfer medium flowing through conduits 54 and 55 with engine coolant flowing through coolant conduits 96 and 98. In this example a continuous belt 32 operatively connects sheave 34 of the engine, shown in FIG. 3, to sheave 36 of the compressor. There is a valve 40, in this particular example a 4-way, 2 position valve, which is used to select an air-conditioning mode or a heat pump mode as described in more detail below. An expansion valve 42, in this case a capillary tube, acts as an expansion device.

There is a first conduit 51 connected to output port 60 of the compressor, a second conduit 52 connected to a first port 62 of the heat exchanger, a third conduit 53 connected to port 64 of the heat exchanger and a fifth conduit 55 connected to port 68 of the evaporator. There are a sixth conduit 56, a seventh conduit 57 and an eighth conduit 58. Conduit 56 connects port 66 of the condenser to the fifth conduit 55 and to the eighth conduit 58. The seventh conduit 57 is connected to input port 70 of the compressor.

The valve 40 has four ports 81, 82, 83 and 84. Port 81 is connected to the seventh conduit 57. Port 82 is connected to second conduit 52. Third port 83 is connected to conduit 51, while fourth port 84 is connected to eighth conduit 58.

The valve has a valve member or spool 90 which is movable to two different positions, shown in FIGS. 1 and 2, by means of an actuator 92, in this case a solenoid. In the air-conditioning mode, shown in FIG. 1, the valve member connects second port 82 to the first port 81 and connects the third port 83 to the fourth port 84. Alternatively, in the heat pump mode shown in FIG. 2, the valve member connects the third port 83 to the second port 82 and connects the fourth port 84 to the first port 81.

The coolant conduits 96 and 98 extend from the engine 30 to the evaporator 26 for providing hot coolant from the engine to the evaporator and for returning the coolant to the engine.

There is a first one-way valve 100 positioned along ninth conduit 59 which prevents a flow of fluid toward the condenser 24. A second one-way valve 102 is located along fifth conduit 55 and prevents a flow of fluid toward the evaporator 26.

During the air-conditioning mode, as shown in FIG. 1, heat transfer medium is fed into input port 70 of the compressor 28 through the seventh conduit 57 and is compressed by the compressor, discharged through port 60 and passes through the first conduit 51 to third port 83 of the valve 40. The heat transfer medium then passes from port 84 of the valve through conduits 58 and 56 to condenser 24. The medium cannot flow into the evaporator 26 due to the action of one-way valve 102. The medium is condensed in the condenser and then passes through capillary tube 42 where the medium is depressurized and passes through heat exchanger 12 which acts as an evaporator during the air-conditioning mode. The fan 16 forces air through the heat exchanger 12, thereby cooling the air for the interior 20 of the vehicle.

Referring to FIG. 2, this shows the apparatus 10 in the heat pump mode. Here the valve 40 connects port 83 to port 82 and connects port 84 to port 81. Heat transfer medium compressed by the compressor exits through output port 60 of the compressor and enters port 62 of the heat exchanger 12 via conduits 51 and 52. In this mode, the heat exchanger acts as a condenser. The fan 16 forces air through the heat exchanger 12, thereby heating the cab and cooling the medium to condense the medium. The condensed medium passes through capillary tube 42, via conduit 53, where it is depressurized and enters port 67 of the evaporator 26 via conduit 54. The medium is prevented from entering the condenser 24 by one-way valve 100. In the evaporator, the heat transfer medium is heated by hot coolant from the engine 30 circulated through the evaporator by conduits 96 and 98. The evaporated medium is drawn into the input port 70 of the compressor via conduits 55, 58 and 57 and ports 84 and 81 of the valve 40. The medium does not enter the condenser through conduit 56 due to higher pressure on the opposite side of the condenser. Thus it may be seen that the interior of the vehicle is heated by energy transferred from the engine 30, both from coolant flowing through the evaporator 26 and by the energy applied to the compressor 28 by the engine 30.

It will be understood by someone skilled in the art that many of the details provided above are by way of example only and can be varied or deleted without departing from the scope of the invention which is to be interpreted with reference to the following claims. 

1. A combined heat pump and air-conditioning apparatus, comprising: a heat exchanger; a condenser; an evaporator; an internal combustion engine; a compressor operatively connected to the engine, the compressor having an input port and an output port; a valve; a first conduit connected to the output port of the compressor; a second conduit connected to the heat exchanger; a third conduit connected to the heat exchanger; a fourth conduit connecting the third conduit to the evaporator; a fifth conduit connected to the evaporator; a sixth conduit connected to the condenser; a seventh conduit connected to the input port of the compressor; an eighth conduit connected to the sixth conduit and the fifth conduit; a ninth conduit connected to the condenser and to the third conduit; coolant conduits connecting the engine to the evaporator for supplying heated engine coolant to the evaporator; and a valve having a first port, a second port, a third port, a fourth port and a movable valve member for interconnecting the ports, the first port being connected to the seventh conduit, the second port being connected to the second conduit, the third port being connected to the first conduit and the fourth port being connected to the eighth conduit, the apparatus having an air-conditioning mode where the valve member connects the second port to the first port and connects the third port to the fourth port, whereby a heat transfer medium compressed by the compressor flows to the condenser through the first conduit, the eighth conduit and the sixth conduit, the heat transfer medium flowing from the condenser to the heat exchanger through the ninth conduit and the third conduit and flows from the heat exchanger to the input port of the compressor through the second conduit and the seventh conduit, the apparatus having a heat pump mode where the valve member connects the third port to the second port and the fourth port to the first port, whereby the heat transfer medium compressed by the compressor flows to the heat exchanger through the first conduit and the second conduit, flows from the heat exchanger to the evaporator through the third conduit and the fourth conduit, the heat transfer medium flowing from the evaporator to the input port of the compressor through the fifth conduit, the eighth conduit and the seventh conduit.
 2. The apparatus as claimed in claim 1, including a first one-way valve along the ninth conduit which prevents fluid from flowing from the third conduit into the condenser, whereby the heat transfer medium flows from the heat exchanger to the evaporator in the heat pump mode.
 3. The apparatus as claimed in claim 2, including a second one-way valve along the fifth conduit which prevents heat transfer medium from flowing from the eighth conduit to the evaporator during the air-conditioning mode.
 4. The apparatus as claimed in claim 3, wherein the heat exchanger has a first port and a second port, the second conduit being connected to the first port of the heat exchanger and the third conduit being connected to the second port of the heat exchanger, the second port of the heat exchanger being an input port for the heat exchanger and the first port of the heat exchanger being an output port for the heat exchanger during the air-conditioning mode, the first port of the heat exchanger being an input port for the heat exchanger and the second port of the heat exchanger being an output port for the heat exchanger during the heat pump mode.
 5. The apparatus as claimed in claim 4, including an expansion device along the third conduit.
 6. A combined heat pump and air-conditioning apparatus, comprising: a source of heat; a compressor having an input and an output; a heat exchanger; an air-conditioning condenser; a heat pump evaporator; first conduits for connecting the source of heat to the heat pump evaporator; heat transfer medium conduits interconnecting the heat exchanger, the air-conditioning condenser and the heat pump evaporator; and a valve operatively connected to the medium conduits and connecting the output of the compressor to the air-conditioning condenser and connecting the heat exchanger to the input of the compressor during an air-conditioning mode where the heat exchanger operates as an air-conditioning evaporator, the valve operatively connecting the output of the compressor to the heat exchanger and connecting the input of the compressor to the heat pump evaporator during a heat pump mode where the heat exchanger acts as a heat pump condenser.
 7. The apparatus as claimed in claim 6, wherein the air-conditioning condenser is connected by the medium conduits to the heat exchanger during the air-conditioning mode whereby the heat transfer medium flows from the air-conditioning condenser to the heat exchanger and the heat pump evaporator is connected to the heat exchanger during the heat pump mode, whereby the heat transfer medium flows from the heat exchanger to the heat pump evaporator.
 8. The apparatus as claimed in claim 6, wherein the source of heat is an engine, the first conduits carrying coolant from the engine to the heat pump evaporator, the engine being operatively connected to the compressor for powering the compressor.
 9. The apparatus as claimed in claim 6 including one-way valves preventing the heat transfer medium from flowing through the air-conditioning condenser during the heat pump mode and preventing the medium from flowing through the heat pump evaporator during the air-conditioning mode.
 10. A vehicle having an interior, an internal combustion engine and a combined heat pump and air-conditioning apparatus, the apparatus having a compressor with an input and an output; a heat exchanger communicating with the interior of the vehicle; an air-conditioning condenser; a heat pump evaporator; heat transfer medium conduits for a heat transfer medium, the medium conduits interconnecting the heat exchanger, the air-conditioning condenser and the heat pump evaporator; coolant conduits interconnecting the heat pump evaporator and the engine for carrying coolant heated by the engine; a valve operatively connected to the medium conduits and connecting the output of the compressor to the air-conditioning condenser and connecting the heat exchanger to the input of the compressor during an air-conditioning mode where the heat exchanger operates as an air-conditioning evaporator, the valve operatively connecting the output of the compressor to the heat exchanger and connecting the input of the compressor to the heat pump evaporator during a heat pump mode where the heat exchanger acts as a heat pump condenser.
 11. The vehicle as claimed in claim 10, wherein the engine is an auxiliary engine having a liquid coolant.
 12. The vehicle as claimed in claim 10, wherein the air-conditioning condenser is connected by the heat transfer conduits to the heat exchanger during the air-conditioning mode whereby the heat transfer medium flows from the air-conditioning condenser to the heat exchanger and the heat pump evaporator is connected to the heat exchanger during the heat pump mode, whereby the heat transfer medium flows from the heat exchanger to the heat pump evaporator.
 13. The vehicle as claimed in claim 10, the engine being operatively connected to the compressor for powering the compressor.
 14. The vehicle as claimed in claim 10, including one-way valves preventing the heat transfer medium from flowing through the air-conditioning condenser during the heat pump mode and preventing the medium from flowing through the heat pump evaporator during the air-conditioning mode.
 15. The vehicle as claimed in claim 10 including an expansion device between the heat exchanger and the heat pump evaporator during the heat pump mode and between the air-conditioning condenser and the heat exchanger during the air-conditioning mode.
 16. A method of heating and cooling a space having a heat exchanger and a fan for directing air over the heat exchanger into the space, the method comprising: cooling the space during an air-conditioning mode by connecting an output of a heat transfer medium compressor to an air-conditioning condenser, connecting the air-conditioning condenser to the heat exchanger and connecting the heat exchanger to an input of the compressor, whereby the heat exchanger and fan acts as an air-conditioning evaporator for cooling the space; and heating the space during a heat pump mode by connecting the output of the compressor to the heat exchanger, connecting the heat exchanger to a heat pump evaporator and connecting the heat pump evaporator to the input of the compressor.
 17. The method as claimed in claim 16, wherein the heat pump evaporator is heated by coolant from an internal combustion engine.
 18. The method as claimed in claim 17, wherein the compressor is powered by the internal combustion engine.
 19. The method as claimed in claim 18, wherein the transfer medium is prevented from flowing through the heat pump evaporator during the air-conditioning mode and is prevented from flowing through the air-conditioning condenser during the heat pump mode.
 20. The method as claimed in claim 16, wherein the space is an interior of a vehicle.
 21. The method as claimed in claim 20, wherein the connections between the heat pump evaporator, the air-conditioning condenser and the heat exchanger are changed by a valve. 